johnston



F. B. JOHNSTON.

HOISTING ATTACHMENT FOR SCAFFOLDS.

\PPucAnoN FILED 0:0. 3; m9.

1,388,262 Patenwd Aug. 23, 1921.

2 SHEETS-SHEET I.

F. B. JOHNSTON.

HOISTING ATTACHMENT ron SCAFFOLDS.

APPLICATION FILED DEC. 3, 199.

1,388,262. Patenflad Aug. 23, 1921.

2 SHEETS-SHEET 2.

4 47 .79 4 ,7 INVENTOR I Q 4% n 1/ By K 1! I I as ATTORNEY UNITED STATESPATENT OFFICE.

rum: 3. :romrsron, or ROSELLE 2m, New JERSEY, ASSIGNOR T0 AMERICANsAEE'rY DEVICE 00., or NEW YORK, 11. Y.

EOISTING ATTACHMENT FOE SCAFFOLDS.

Specification of Letters Patent.

Patented Aug. 23, 1921.

To all whom it may concern:

Be it known that I, FRANK B. JOHNSTON, a citizen of the United States,and a resident of Roselle Park, county of Union, and State of NewJersey, have invented certain new and useful Improvements in HoistinAttachments for scaffolds, of which the f0 lowing is a specification. I

The present invention relates to improvements in hoisting attachmentsfor scaffolds, and I particularly propose in the present disclosure toprovide a device especially desirable for scaffolds of the swingingladder type such as are used by painters, stone setters, stucco workers,renovators, etc., althou h it will be understood that it may be use forother types of scaffolds and in other connections where it is desired toraise and lower a latform.

eretofore painters scaffolds have been supported and hoisted for themost part by a block and fall arrangement, which was dangerous,laborious to operate, and was attendant with many disadvantages whichmade it undesirable. The Manila rope was easily affected by weatherconditions and by acids and whitewash which tended to decay anddeteriorate it, a great deal of surplus rope had to be carried on theplatform, encumbering the workmen, or piled upon the ground forming anobstruction, and its security was never of such a positive nature as toinsure against accidents, the support of the scaffold de ending entirelyupon the reliability with w iich the workmen fasten the rope.

It is an object of the present invention therefore, to provide a deviceof relatively light weight, easy to o erate both in raising and loweringthe sea old, compact so that the working room of the workmen is notsacrificed or impaired, and having a maximum of safety. A further objectresidesin providing a device which may be used in substitution of theblock and fall, utilizing the usual form of rigging at present employedupon painters scaffolds, and of which a great many are in use, that is,the device may be directly attached to the means provided on thescaffold to which the usual block and fall is attached. I furtherpropose to facilitate the rigging up of the de vice, enabling thesuspension cable to be freely spun off the drum, it being proposed topermit disengagement of the winding drum upon which the cable isprovided from its holding means, and its free rotation in eitherdirection when desired. A further object is to provide a machine whichmay be operated from the scaffold when desired.

Other objects are rigidity between the winding drum and the scaffoldfloor, thereby obtaining a maximum of power, positioning of the deviceso that the man operating the same may stand properly balanced upon thescaffold permitting him to work the device with the least danger tohimself and without loss of power, and facility of attachment to thescaffold, the attachment means carried by the device constituting alsotools for carrying out the attachment operation. A further object is toprovide a device which may be raised with relative speed and loweredwith rapidity and steady control, and with a maximum of safety in eithercase.

With these and other objects in view, an embodiment of my invention isshown in the accompanying drawings, and this embodiment will behereinafter more fully described with reference thereto, and theinvention will be finally pointed out in the claims.

In the accompanying drawings,

Figure 1 is a side elevation showin a painters scaffold of the swingingla der type provided with an embodiment of my hoisting device;

Fig. 2 is a plan view thereof;

Fig. 3 is a perspective view looking from one end of the scaffold;

Fig. 4 is a front elevation of the hoisting device according to thepresent embodiment of my invention;

Fig. 5 is a side view thereof;

Fig. 6 is a fragmentary view showing the worm gear employed thereinshifted during raising of the scaflold;

Fig. 7 is a similar view showing the worm gear retained in shiftedposition to free the drum therefrom;

Fig. 8 is a front view of the ratchet engaging dog provided on the handlever for raising the scaffold;

Fig. 9 is a top view thereof;

Fig. 10 is a detail sectional view taken along the line 1010 of Fig. 4;Fig. 11 is a similar view taken along the line 1111 of Fig. 6; and

Fig. 12 is a side view of a machine showing means for operating it fromthe ground.

Similar reference characters indicate corresponding parts throughout theseveral figures of the drawings. L

Referring to the drawings, and particularly to Figs. 4 to 11 thereof,the machine according to the present embodiment of my in-- a rod 14having mounted thereon a rotatable shift pulley wheel 15, looselyslidable sleeves 16 and 17 being disposed at each side thereof. Theperiphery of the groove of the pulley wheel is in a vertical line withthe axis, of the shaft of the drum so that the cable 18extending fromthe drum is in a direct vertical line with the axis of the drum, theshifting of the pulley permitting the cable to be wound evenly upon thedrum.

The lower end 19 of the frame is formed of a separate piece from theuprights, its upwardly bent end portions being secured to the lowerends, of the uprights by bolts and nuts 20. To the portion 19 there issecured by a bolt 21, an inverted U-shaped clamping strap 22 having itsside portions.

disposed at an angle and connected by spaced bolts 23 and 24 alsoangularly disposed, the bolts 23being secured by a nut 25, while thebolt 24 is secured by engagement with the threaded hole 26 provided atone end of a wrench 27, the other end thereof being provided with asquared aperture 28 adapted to engage the nut 25 to remove or secure it.

The drum 10 comprises a hub upon which the cable 18 is wound, and sideflanges or cheeks 29 and 30, the hub being loosely mounted to turn on.the shaft 11, theche'ek 29 being substantially of greater thickness thanthe check 30 and provided at itsperiph-- ery with ratchet teeth 3lengaged by a pawl 32 pivotally supported by a pin 32 upon the upright ofthe frame. During lowering of the machine, as will hereinafter be morefully pointed out, the pawl 32 is disengaged from the ratchet 31 bythrowing the same over so that its upper surface rests without effectupon the surface of the teeth'as indicated indottedlines in Fig. 5.

A hand lever 33 is pivotally mounted on the shaft 11 between the cheek29 and the adjacent upright portion of the frame and has mounted thereona sliding dog comprising a face plate 34 extending over the inner sideof the ratchet, and a toothed block 35 secured thereto and adapted toengage the teeth of the ratchet. A strap member 36 is secured at itsendsto the face plate and extends about the lever, and to this strapmember vthere is secured a block 37 adapted to weight "the dog to causeit to slide readily into and out of engagement with the teeth by gravityas the hand lever is raised and lowered. When the hand lever is notbeing operated it is normally in its lowered position, the dog fallingvout of engagement with the ratchet by gravity.

The shaft 11 is provided at the side of the cheek 30 with an enlargedportion 38 upon which there is slidably and rotatably mount ed a wormgear 39 having radialratchet teeth 40 provided at its inner side adapted.to engage the radial ratchet teeth 41 provided upon the outer side ofthe cheek 30 of the drum, a spring 42 disposed on the shaft 11 betweenthe worm gear 39 and the side frame constantly forcing the ratchet teeth40in yielding engagement with the teeth 41.

The'worm' gear is engaged by a worm 43 having its shaft 44 journaled inthe ends of a bracket 45, one end of the shaft being. extended andprovided with a squared portion 46 adapted to be engaged by a handle 47to turn the worm. Shoulders 43 and 43* are provided upon the worm,spaced from the ends of the bracket 45 so that the worm may shiftlongitudinally, a coil spring 43 forcing the worm when it is unresistedrear wardly so that the shoulder 43 is abutted by the rear end of thebracket as shown in Figs;

6 and 11. The dimensions of the worm and worm gear are suchlthat thegear may be shifted upon its shaft to disengage the ratchet teeth 40from the teeth 41, without the teeth of the worm gear becomingdisengaged from the worm, the worm constantly acting as apositive lockto the worm gear.

Normally when the machine is suspended by thev cablev and at rest, orduring lowering. when the pull of the cable forces the drum in adirection to turn the worm gear with it, the worm is forced. forwardlyaga nst the force of the spring 43 with the shoulder 43 abutting againstthe forward end. of the bracket 45, as indicatedv in Figs. 4, 5 and 10.During raising of the machine, the ratchet a force exerted against theface of the ratchet teeth 40. Should for any reason the pawl 32,preventing backward movement of the drum during raising, fail, theratchet teeth Fig. 4.

40 of the worm gear will be engaged by the ratchet teeth 41 of the drum,and will be allowed to be fully engaged by expansion of the spring 42before the actual resistance afforded by the worm gear; and wormbecomesefi'ective incident to the yielding of the spring 43. Thus anydanger of stripping the teeth is prevented as would be the case if theworm gear were held rigidly and the ends of its ratchet teeth 40suddenly and forcibly engaged by the ratchet teeth 41.

Upon the side of the frame there is pivotally mounted a dog 48 which maybe swung downwardly to enga the inner face of the worm gear to hold t eratchet teeth 40 outof engagement with the ratchet teeth 41. If, at thesame time, the pawl 32 is disengaged from the ratchet teeth 31 of thecheck 29, the drum will be free to rotate in either direction, so thatthe cable may be rapidly run off the drum, thereby facilitating the riging up of the scaffolds upon the ground. The dog 48 may if desired, bemounted below the worm gear to beswung up into holding position.

he frame 13 has a thumbscrew 13, which is screw-threaded throughout itslength, and engages screw-threads 13 in the member 13. The gear 39 has arecess 39, which is provided with screw-threads. When the recess 39 isin registration with the screw 13, the gear 39 is moved to the positionindicated in Fig. 7, with the teeth 40 and 41 disengaged, and thethumbscrew 13 is turned so as to have its threads engage the threadedrecess 39* of the gear 39, and when such engagement takes place, thegear 39 is held toward the frame 13, and when so held in position, thereis no possible chance of the ratchets 40 and 41 engaging with eachother. On the other hand, the thumbscrew may be again disengaged fromits threaded recess, and moved out to a position sufficiently far toallow for the play of the movable gear 39 with its ratchet 40, as shownin Fi 4 and 6. The object of this is to limit t e movement of the gear39, and prevent its movement beyond a desired position, that is, aposition be 0nd that necessary to permit its play to an fro.

When the ratchets 40 and 41 mesh, the thumbscrew is moved so that itsend is inward, close to the gear 39, with simply a slight clearancebetween the end of the screw and the ear 39, as shown in dotted lines,hen on the rotation of the gear, there will be no engagement between therecess of the gear and the thumbscrew, and the thumbscrew will act as anabutment limiting the movement of the gear. By the positioning of thescrew into this position, the ratchet 40 will be held againstdisengagement from the ratchet 41, and the desired engagement will bemaintained. The thumbscrew thus serves three objects; first, to holdpositively the ratchet 40 out of mesh with the ratchet 41; secondly, tolimit the movement of the gear 39 in one direction, and thirdly, to holdthe gear in a definite position, so that the ratchets continuallyintermesh. In its function of holding the ratchet 41 out of engagementwith the ratchet 40, the thumbscrew 13 may act either in cooperationwith or independently of the dog 48.

The scaffold illustrated is of the usual ladder type employed bypainters, consisting of the platform 49 provided at its ends withscaffold irons 50 and 51 of inverted V- shape, and looped as at 52 attheir apices. The machines are secured to these irons by engaging thestrap 22 about the loops 52, the bolt 23 being first secured through theloop, its nut 25 being tightened by means of the wrench 27. The bolt 24is placed beneath the loop, and is secured in place by engaging thethreaded end of the wrench therewith. This method of securing makes themachine substantially rigid with the scaffold irons. The frame being atan angle to the irons, the angular disposition of the strap 22 causingthe frame to assume this position, results in the hand levers extendingat the sides of the scaffold so that a free space is provided in frontof the machine substantially the full width of the scaffold, and theworkman may therefore stand in the center of the scaffold and properlybalance himself during raising and lowering of the scaffold.

In order to raise the scaffold, the hand lever 33 is raised to its upperposition so that its sliding dog engages the teeth of the ratchet, andby moving the same downwardly, the drum is turned and the cable woundthereon, the raising of the scaffold being relatively ra id. Durin thisaction, the pawl 32 engaging the rate et, prevents back movement whilethe drum is additionally locked against back movement by the worm gearand worm, the large bearing surface provided by the teeth of theratchets 40 and 41 and the positive locking action of the worm affordinga positive, powerful, efficient and evenly distributed control. As thedrum is turned in the direction to wind the cable thereon, the ratchetteeth 41 exert a cam action on the worm gear shifting it outwardly, thespring 42 immediately returning it as the teeth of the ratchet 40 passover the points of the teeth of the ratchet 41 so that during hoistingthe worm is constantly yieldable to permit of the hoisting movement, andat the same time is constantly in position to prevent backward movement.

In lowering the scaffold, the pawl 32 is disengaged from the ratchet 31,and by turning the worm by means of the handle 47, the ca le islet offfrom the drum and the scaffold descends, the constant and positive lockafforded by the worm permitting the descent with a maximum of safety,and with the least expenditure of time and exertion on prevent orproduce'backward motion, said 65 means of said worm gear being yieldablethe part of the workmen. The uncertainty and danger of the block andfall and the necessity for untying and'tying hitches in the ropewhenever it is desired to raise or vlower the scaffold are entirelyeliminated.

The machines are compact, light in weight, powerful and positive intheir action, and entirely safe, the safety clutch provided by the wormbeing at all times in automatic engagement. The cable need only be of alength corresponding to the drop of the scaffold, the surplus cablebeing wound upon the drum and therefore entirely out "of the way of theworkmen.

In Fig. 12, I have shown the manner in which the machine may be operatedfrom the ground to raise the scaffold without any one on it. Upon theend of the hand lever '33 there are provided a pair of rings 55 and 56to which are secured ropes or cables 57 and 58 extending to the ground,the rope 58 being first carried in a loop over one of the sleevesprovided on the rod 15. By pulling upon the rope 58, the hand lever ismoved to its raised position, the ratchet dog automatically falling intoengagement with the teeth. of the ratchet, and by pulling on the rope 57the lever is lowered turning the drum and winding the cable thereon, andby continuing this operation alternately, first pulling on one rope andthen on the other, the scaffold is raised. The scaffold irons are heldagainst slippage on the platform by means of staples and pins and 61embracing the sides of the irons.

I have illustrated and described a preferred and satisfactory embodimentof my invention, but it is obvious that changes may be made thereinwithin the spirit and scope thereof as defined in I claim:

1. In a hoisting and lowering means for scaffolds, a frame, a drum inthe frame adapted to receive a cable thereon, operating means forturning the drum whereby to hoist the frame on the cable, and a holdingpawl adapted to maintain the drum from turning in a reverse direction,in combination with a yieldable normally inactive rethe appended claims.

verse preventing means for the drum a'dapted to normally permit freeoperation of the latter and adapted to hold the drum from reversemovement and absorb shock imposed on the drum when said pawl fails tooperate.

2. A hoisting and lowering machine for scaffolds, comprising a drum, aframe supporting said drum, releasable means adapted to operate the drumin hoisting direction, a ratchet rotatable with said drum, a worm gearhaving means engaging/the teeth of sald ratchet, a .worm engaglng saldworm gear,'sa1d worm and wormgear adapted to axially away from saidratchet of said drum to permit rotation of said drum in a hoistingdirection.

3. A hoisting and lowering machine for scaffolds, comprising a drum, aframe, a

shaft carried by said frame supporting said drum, releasable meansadapted to operate the drum in hoisting direction, and steady controland operating means comprising a worm gear on-said shaft, a ratchetfixed to said drum, a ratchet rotatable with said Worm gear, a wormengaging said worm 'gear, and spring means retaining said ratchet ofsaid worm gear in axially yielding engagement with said ratchet of saiddrum.

4. A hoisting and lowering machine for scaffolds, comprising a drum, aframe, a

shaft carried by said frame supporting said drum, releasable meansadapted to operate the drum in hoisting direction, a worm gear' on saidshaft, a ratchet fixedto said drum,

a ratchet fixed to said worm gear, a worm ngaging said worm gear, andspring means retalnlng sald ratchet of sad worm gear in axially yieldingengagement with said ratchet'of said drum, said worm gear adapted toshift upon said shaft against the force of said sprlng means as saiddrum is op-' erated in hoisting direction, and adapted during saldshlftlng to malntain constant engagement with said worm.

5. A hoisting and loweringmachineforrotatable with-said worm gear, andspring means retaining said ratchet of said worm gear in' axiallyyielding engagement with said ratchet of said drum.

6. A hoisting and lowering machine for scaffolds, comprising a drum, aframesupporting said drum, means, adapted to operate said drum inhoisting directiommeans carried by said frame adapted to cooperate withthe drum to prevent or produce backward, motion, while automaticallypermitting the forward hoisting motion, and I means rendering said lastnamed means yieldable to a limited degree against the force of thebackward motion of said drum.

7. A hoisting and lowering machine for scaffolds, comprising a drum, aframe supporting said drum, means adapted to opcrate said drum inhoisting direction, a.

worm gear, and a worm adapted to cooperatelwith the drum to prevent orproduce backward motion, while automatically permitting the forwardhoisting motion, said worm gear and worm being yieldable to a limiteddegree against the force of the backward motion of said drum.

8. A hoisting and lowering machine for scaffolds, comprising a drum, aframe, a shaft carried by said frame supporting said drum, flanges ateach end of said drum, ratchet teeth upon one of said flanges, a handlever pivoted at the axis of said drum, a sliding dog on said hand leveradapted to drop by gravity into and out of engagement with said ratchetas said hand lever is raised and lowered, a pawl engaging said ratchetto prevent backward movement of said drum, operation of said hand leveradapted to operate said drum in hoisting direction, and means foroperating said drum in lowering direction when said hand lever and saidpawl are released.

9. A hoisting and lowering machine for scaffolds, comprising a drum, aframe, a shaft carried by said frame and supporting said drum, a cablewound on said drum and extending upwardly therefrom, a shaft at theupper end of said frame, a pulley slidable on said shaft and adapted toguide said cable upwardly in vertical line with the axis of said drum,sleeves on said shaft at the sides of said pulley adapted to limit thesliding movement thereof, releasable means for operating the drum inhoisting direction, and means for operating the drum in loweringdirection when said first named means is released.

10. A hoisting and lo'wering machine for scafi'olds, comprising a drum,a frame supporting said drum, releasable means adapted to operate thedrum in hoisting direction, a ratchet rotatable with said drum, a wormgear having means engaging the teeth of said ratchet, a Worm engagingsaid worm gear, said worm and worm gear adapted to prevent or producebackward motion, and means carried by said frame adapted to maintainsaid means of said worm gear in engagement with said ratchet.

11. A hoisting and lowering machine for scaffolds, comprising a drum, aframe supporting said drum, releasable means adapted to operate the drumin hoisting direction, a ratchet rotatable with said rum, a worm gearhaving means engaging the teeth of said ratchet, a Worm engaging saidworm gear, said Worm and worm gear adapted to prevent or producebackward motion, said means of said worm gear being yieldable axiallyaway from said ratchet of said drum to permit rotation of said drum in ahoisting direction, and means carried by said frame adapted to limit theaxial movement of said means of said worm gear.

In testimony that I claim the foregoing as my invention, I have signedmy name hereunder.

FRANK B. JOHNSTON.

